Modern engines vs older engines

Beano

Beano

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I'm interested in knowing the differences between modern and older (up to say, 1970s or 80s) engines. Mostly because my mind still operates on old information and I don't want to stuff up any cars I may own at the moment or the future, by poor management / maintenance.

For instance, I have heard that modern piston rings have much less tension on them, and that with the increase in recommended oil change intervals, the oil scraper rings can become clogged up and not seal, causing excessive oil usage and (somehow) cylinder wear. I guess the lesson is to change oil at 10,000 Ks, regardless of manufacturer recommendations.

Anything else ?

I invite comment from anyone on this general topic.
 
On the electrics side, you need to be sure you can jumpstart a newer car without damaging the electronics.

The smarts in cars now means faults can appear to persist after repair until a reboot is done.
 
Beano said:
I'm interested in knowing the differences between modern and older (up to say, 1970s or 80s) engines. Mostly because my mind still operates on old information and I don't want to stuff up any cars I may own at the moment or the future, by poor management / maintenance.

For instance, I have heard that modern piston rings have much less tension on them, and that with the increase in recommended oil change intervals, the oil scraper rings can become clogged up and not seal, causing excessive oil usage and (somehow) cylinder wear. I guess the lesson is to change oil at 10,000 Ks, regardless of manufacturer recommendations.

Anything else ?

I invite comment from anyone on this general topic.
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My Diesel Koleos (2008) has a 15,000 km or 12 months oil change period. It doesn't use a skerrick of oil in either 12 months or 15,000 km. The other half's Megane 1.2 Intens Turbo Auto sedan (2017) has a 30,000 km/ 12 month service interval. It doesn't uses any oil over the twelve months either although it never gets up to the 30K. The oils and metallurgy used nowadays are genuinely rocket science!
 
Some engines, such as the 5 cylinder engines found in Mazda BT50 and Ford Ranger until recently, one needs to change the oil in under 10 minutes, because the variable flow oil pumps can not self prime if they are drained of oil. Potential opps is likely to be very expensive.
 
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Kim Luck said:
My Diesel Koleos (2008) has a 15,000 km or 12 months oil change period. It doesn't use a skerrick of oil in either 12 months or 15,000 km. The other half's Megane 1.2 Intens Turbo Auto sedan (2017) has a 30,000 km/ 12 month service interval. It doesn't uses any oil over the twelve months either although it never gets up to the 30K. The oils and metallurgy used nowadays are genuinely rocket science!
Click to expand...
My 2002 Laguna V6 has 30,000 Km 2 year service intervals, it has 236,000 Km on the odometer and does not get topped up between services. The last 3 services I have taken it out to the full 30,000 Km as I have been doing quite a few K's over the past 3 years.

Its not only metallurgy but modern oils, fuels and electronic control of the combustion process that contributes to long service interval.

Having said all that those service intervals are for best operating conditions, I do most of my K's on country roads so if you spend all your life driving your car in a city doing short trips it would be wise to re-think the service intervals.
 
FIVEDOOR said:
Some engines, such as the 5 cylinder engines found in Mazda BT50 and Ford Ranger until recently, one needs to change the oil in under 10 minutes, because the variable flow oil pumps can not self prime if they are drained of oil. Potential opps is likely to be very expensive.
Click to expand...
I have heard that, you would almost want to put the sump plug back in and fill it with oil straight away and start it up and prime the system when most of the oil has drained out.
 
I think as others have said the greatest difference is in engine management so far as engine longevity is concerned.
A mate of mine used to run a mechanical business and a large part of his trade was fitting exchange engines. He said once Ford and Holden started injecting their old cast iron 6s they simply stopped clapping out by 160- 200,000kms like the carby versions were.
Cold starts with carburation is when most wear occurs due to fuel wash on the cylinder walls.
Hence old 70s/80s taxis on LPG would do astronomical mileage compared to the same type of car running on petrol.
Poorer combustion with carburation also means more carbon contaminants getting into the engine oil which also exacerbates wear.
I once bought a one owner carburettored, dual fuel, ex taxi XE Falcon with over 650,000kms on it. It was on its 3rd automatic transmission, but the original engine was untouched and still ran sweet as a nut.🤷‍♂️
 
Modern engines shouldn’t be warmed up. Although much less of a problem than the old carburettor days, a rich mixture at cold idle just washes oil off the bore and you do more damage letting it idle cold than moving off straight after start up and warming it fast under moderate loads.

If I could only convince my neighbour of this as he warms up his injected motorcycle at 5 fucking am every morning…
 
The only reason to warm up was carburettors ran like crap cold, but injection computers solve that. And especially combined with modern oils that properly circulate in seconds the warm up is obsolete.
 
Haakon said:
Modern engines shouldn’t be warmed up. Although much less of a problem than the old carburettor days, a rich mixture at cold idle just washes oil off the bore and you do more damage letting it idle cold than moving off straight after start up and warming it fast under moderate loads.

If I could only convince my neighbour of this as he warms up his injected motorcycle at 5 fucking am every morning…
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I remember when Holden first injected their old cast iron 6 one of their claims was "full power from right from cold start".

I've just pulled up at work in my carburettored van. Chilly here this morning and it ran like crap for the first couple of kays.😉
 
Haakon said:
Modern engines shouldn’t be warmed up. Although much less of a problem than the old carburettor days, a rich mixture at cold idle just washes oil off the bore and you do more damage letting it idle cold than moving off straight after start up and warming it fast under moderate loads.

If I could only convince my neighbour of this as he warms up his injected motorcycle at 5 fucking am every morning…
Click to expand...

Well..... this fact is unexpected, but I see the logic in it.

Thanks to all for your input.
 
Haakon said:
Modern engines shouldn’t be warmed up. Although much less of a problem than the old carburettor days, a rich mixture at cold idle just washes oil off the bore and you do more damage letting it idle cold than moving off straight after start up and warming it fast under moderate loads.

If I could only convince my neighbour of this as he warms up his injected motorcycle at 5 fucking am every morning…
Click to expand...
Haakon said:
The only reason to warm up was carburettors ran like crap cold, but injection computers solve that. And especially combined with modern oils that properly circulate in seconds the warm up is obsolete.
Click to expand...

A few words from Iain Tyrrell

 
Hi :2cents:
I would not be worried about the differences in modern engines. Just do what is recommended. They work great and many many design hours go into them, not only for longevity but reduction of pollution in use and servicing and safer materials. Wonderful. We just get in and drive them and are not tied to them as machines really like we were. The rings have less tension and the clearances and oil and materials are designed for reduced friction but we get better fuel economy as a bonus. They are lighter and plastic but we get the bonus for that too !:cool:

There could be some mistakes and possibly some lemons but really that is relative, because most old engines would be lemons if you gave one to a young person today. My kids just drive their cars and do nothing to them. I am at call if needed but really it does not happen much. I try to give them a service every now and again and a look over. Not like the good ol'days when I was young and we had to tinker to keep them going, for sure.:rolleyes:

And I might add the bodies last better now also. The paint is thinner and the metal but better and the design does not include the rust traps built in to the front air system and the doors and guard tops etc like they were back then. In 10 years the old cars could have serious rust and the muffler fell apart too. Now the inspection hardly looks for rust in new cars because it is not common at all.:love::love: .
Jaahn
 
One point Iain Tyrell made that I never considered (and I should have) was that a rich mixture at startup is needed simply because the air you're puling in is colder so there's more of it (molar volume is temperature dependent) hence you simply need more fuel to stay stoichiometric.

Other problems we all know about (less vaporisation with cold fuel/air etc.). This is probably more relevant to colder climates, but we have rather cold days here too.

I have eliminated the choke on practically all my cars even back when I lived overseas and preferred to start with a few pumps of the throttle and then floor it through the gears. Maybe not the best way to take care of your car but they served well with no problems.

Another very important comment was brought to my attention some years ago by an engineer who builds custom drag racers. He pointed out that you need the highest oil pressure at idle rather than high revs. Reason is once the rotating assembly is moving fast, if it is correctly balanced it will be in a steady state with minimal oil pressure needed to keep moving parts floating past each other. The situation is very different at idle when the engine "feels" all the fluctuations in strain due to all the movements of all the assemblies (mainly the reciprocating movement of pistons). This is where healthy oil pressure is needed the most to prevent contact.

Which means what?

Well, ideally you should have a dry sump. Max oil pressure at idle from cold.

But if you don't, it is certainly a bad idea to sit there idling with cold oil. Probably much better off to rev it and force that oil everywhere. Yes, things are not going to be at operating temperature, clearances are not going to be optimal, but at least you flood them with oil. I think that might be better than running the engine with tight tolerances and poor (well, low) oil pressure. F1 teams heat all the liquids before starting the engine and their idle is what? 5000 RPM? Something like that? You might burn some oil on startup, but that's okay in my book. Maybe that is why my engines seemed to go well in spite of the treatment I gave them.

I think the trick is to have clearances at optimal temperature and healthy oil pressure right at idle.

One could probably come up with an oil pump drive that would self adjust the opposite way to give max oil pressure at idle and sort of taper off a bit higher in the revs (the bypass valve in modern engines does exactly that). Probably not really necessary with modern engines (let's say my 1987 205GTI engine is "modern") but an interesting thought experiment.
 
The oil pump in the EP series of PSA engines is regulated so that after 2000 rpm it delivers near constant pressure by controlling pump displacement. Up to that speed displacement is
maximum.

PSA mentions that among other things it reduces load on the engine and saves fuel.
 
The EP range of engines are the 1.6 petrol turbos and naturally aspirated engines used by Peugeot and Citroen. in everything from little DS3s to large C5s and 508s.

The pump sits in the sump and is chain driven from the crankshaft. It is a conventional two rotor pump displacing oil between the cogs. The unusual feature is that while the first pumping rotor is fixed on its chain driven axle, the second rotor and its axle are able to slide so that a smaller area inside the outer stator is in mesh.

This is moved by the output pressure acting on a piston whose valve opens at the set oil pressure. A spring returns the mechanism when pressure falls.

At low RPM and lower pressures the device passes full flow rate, after which the displacement is reduced and controlled to maintain constant pressure.
 
I suspect that the output of a pump can be regulated simply by it's displacement, speed and any necessary restriction in it's output galleries? After all this time positive oil pressure and flow is no longer a mystery? There is always someone who can complicate a simple thing. Unless of course, their engines are rubbish and fail because of low starting oil pressures........
 
The point of the PSA pump design is getting maximum possible flow at start. Desirable as this is, the simple pump in older engines doesn't achieve this.
 
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